Dry particle coating: My journey with NMC and Carbon black
My name is Siddhi and I’m currently exploring dry particle coating techniques as part of my PhD research at TU Bergakademie Freiberg. My focus is on using Mechanofusion to coat the cathode active material in Li ion batteries- NMC (Lithium nickel manganese oxide) particles with a conductive additive like carbon black (C65) — without any binders. The goal? Improve electronic conductivity in battery materials while understanding how surface modification influences the structural properties.
Sceptic at First
When I first read about dry coating in a paper, I thought: “There’s no way nano-scale carbon black can stick to anything without a binder!” Fast forward to today, and here I am — deep into mechanofusion trials, tweaking parameters to get just the right coating on NMC particles. Funny how skepticism can turn into fascination.
Oh, this is Hard
Most coventional coating approaches rely on solvents and binders. Using the Picoline machine, which is a machine used for the mechanofusion process, we are trying to achieve a pure dry coating of particles in the labs. I still remember my first trial run with the machine — everything looked perfect on paper until I opened the chamber and saw what looked like soot-covered gravel. That was when I realized… mixing is not coating! Trying to do some surface characterization using Atomic Force Microscopy (AFM) wasn’t easy either. Initially, I kept breaking cantilevers or misaligning the scans. But now, it feels like a quiet ritual: prep, calibrate, scan, breathe.
Oh, this is Small
One of the toughest challenges? To deal with extremely fine particles and to figure out how the coating looks like. Do we have a monolayer (single coating layer of carbon black around NMC), a multilayer (multiple such layers of carbon black) or are the carbon black particles penetrating into the NMC particles? Laser diffraction shows no big size changes due to the nano-sized carbon black used for coating; Scanning electron microscopy (SEM) shows some surface texture — but it’s the AFM that gives it away.
Why this Matters
Everyone in battery materials talks about conductivity and stability, but what if we can influence those just by tuning how particles interact physically — no additives, no chemistry tweaks? That’s what keeps me going — the idea that a simple process can be quite powerful and influential.
What’s next?
This project has taught me patience and how to clean carbon black from everything. But it’s also made me appreciate how much happens at the micro- and nanoscale, and how we can actually control it. Next, I’m hoping to compare the magnetic properties of the coated structures with my previous AFM images using the magnetic force microscopy (MFM). Later, I would explore on how the coating is actually affecting the electronic conductivity of the NMC particles and probably we can have a look together on the main question ‘Did I reach my goal?’ Stay tuned for some MFM fun!
